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Chapter 4 - Onset of impairment

Released: 15 November 2012 Download PDF

Chapter 4 – Onset of Impairment

This data was revised on April 10th 2014

The results presented in this chapter are for those adults with no impairment at Wave One but reported at least one impairment at Wave Two. These adults will be referred to as ‘onset-acquired’.

The longitudinal data collected by LOS allow changes over time to be observed and an onset rate to be calculated to indicate the proportion of adults who had acquired an impairment between Waves One and Two. Section 4.1 describes the calculation of onset rates. Section 4.2 examines the overall rate of impairment onset for the population, as well as examining whether onset rates vary across demographic characteristics. Section 4.3 then describes the types of impairments experienced by this group at Wave Two.

The onset rate used in this report has been calculated as the percentage of all adults without any impairment at Wave One and who were interviewed face to face at Wave Two, who became onset-acquired at Wave Two. The overall onset rate was 13%, meaning that of all adults followed up on the LOS who did not report any impairment at Wave One, 13% subsequently reported at least one impairment at Wave Two. At Wave One, 71% of adults reported no impairment1.

Due to the longitudinal survey design there is a potential measurement bias in the onset rate reported by the LOS. A differential onset rate was identified between the cases identified through the telephone screener, and those identified within face to face sample (i.e. from the ‘control group’ or co-residents of adults with impairments). The weighting method developed for the survey has been designed to adjust for this under estimation, but it should be noted that some bias may remain (see Section 4.1 for further information).

4.1 Survey design implications for the calculation of an overall onset rate

Calculation of the LOS onset rate at Wave Two was complicated by the use of two different methods of follow-up for sub-samples of adults without impairment at Wave One. As a consequence, there is a potential measurement bias in the reported onset rates. At Wave Two, data were collected either via a telephone interview, a face-to-face interview or a combination of the two. As described in the Introduction, a subset of adults without impairments at Wave One were assigned to the “onset-screening” group, who were followed-up prior to Wave Two fieldwork to establish if anyone in their household had acquired an impairment. This telephone interview took place eight months after the Wave One interview. The remainder of adults without impairment at Wave One, who were either in the “control group”, or who were co-residents of adults with impairments or adults in the control group, were followed up with face-to-face interviews 12 months after the Wave One interview.

Thus, adults without impairment at Wave One were followed up either eight months after Wave One (if they were in the onset-screening group) or twelve months after Wave One (if they were in the control group or residents of households receiving face-to-face interviews or they live in a household where someone reported an impairment at the telephone interview). Consequently, a proportion of adults without impairment at Wave One (those in the onset-screening group) would have an unknown impairment status 12 months after their Wave One interview because they received a telephone interview eight months after Wave One. It is likely that some proportion of this group would have acquired an impairment in the four months following their Wave Two telephone interview, but as they were not contacted again, an estimate of this proportion is unknown.

It is also possible that there may be ‘interview mode’ effects that influence whether a person is classified as having an impairment or not, depending on whether they received a telephone or face-to-face follow-up interview1.

The weighting method developed for the survey has been designed to adjust for the underestimation of the onset rate from the telephone screener. But, some bias may remain in the onset rate estimates because it is not possible to fully assess the differences that may be present between onset cases identified through the two modes of the survey.

Despite this potential measurement bias in the onset rate estimates, LOS provides a useful tool for measuring changes in the population with impairments. It provides a sound and consistent measurement of impairment offsets and, arguably, the reported onset rates indicate a valuable measure of the transition into impairment – the onset rate.

Notes for 4.1 Survey design implications for the calculation of an overall onset rate

  1. A telephone interview that indicates an instance of impairment is not in itself sufficient for the classification of impairment.  The classification of impairment can only be made after a further face-to-face interview at Wave Two.  However, it is possible that the initial telephone follow up might miss some instances of impairment that would have been caught with a face-to-face follow up.  In other words, we are protected against mis-identified onset-acquired cases, but not against onset-acquired cases that were not identified during the telephone interview.

4.2 Onset of impairment by demographic characteristics

Table 4.1 presents the onset rate for different sections of the population based on their Wave One demographic characteristics . Alongside the overall onset rate, rates are provided for adults of working age (16 to 64) and adults aged 65 and over. Onset rates rose with age, with those aged 65 and over more likely to acquire an impairment than those of working age. Almost a third (31%) adults aged 75 and over without impairment at Wave One subsequently became onset-acquired at Wave Two, compared with almost one in six (15%) adults aged 45-64, and around one in ten of those aged 25 to 44 (10%) and 16 to 24 (9%).

There are some differences in the onset rate across regions. For example, working age adults living in East of England were more likely to acquire an impairment than those living in the South East or South West. For adults aged 65 and over, those living in East Midlands, East of England and the North East were most likely to become onset-acquired, whereas those living in London and Scotland were the least likely. It is unclear why there are regional variations in the onset rates, although these differences may be explained by factors that are yet to be examined.

Table 4.1, Onset rates by sex, age, ethnicity and region of residence at Wave One [1], and by age

Onset Rate      
Per cent
  Working Age (16 - 64) 65 and over Total
Sex
   Male 9 22 11
   Female 14 24 16
Age
   16 to 24 9 n/a 9
   25 to 44 10 n/a 10
   45 to 64 15 n/a 15
   65 to 74 n/a 19 19
   75 and over n/a 31 31
Working age (16-64) 12 n/a n/a
65 and over n/a 23 n/a
Ethnicity
   White 11 23 13
   Non-White 14 19 14
Region
England 12 23 13
   North East (inc. Yorkshire and Humber) 12 28 14
   North West (inc. Merseyside) 11 21 12
   East Midlands 12 29 15
   West Midlands 10 20 11
   East of England 17 29 19
   London 13 17 13
   South East 9 21 11
   South West 9 26 13
Wales 14 23 15
Scotland 12 16 13
Urban 12 23 14
Rural 10 24 13

Table source: Office for National Statistics

Table notes:

  1. See Appendix 8 for sample size.
  2. n/a - not applicable
  3. All percentages have been rounded to the nearest 1
  4. This data was revised on April 10th 2014

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Table 4.2 presents the onset rates for different groups of the population based on tenure, education and occupation characteristics at Wave One.

The overall onset rate was higher for those owning their property outright (16%) than those who were buying their property with a mortgage or loan (11%). This difference may be explained by the underlying age distributions for the different tenure categories2. In general, people who own their accommodation tend to be older than those with a mortgage. This difference in age distribution for the two tenure categories may therefore explain the higher onset rate among people living in owner-occupier accommodation.

There were some differences in the onset rates across different qualification types, suggesting that attainment of higher qualifications was associated with lower onset rates. For example, the onset rate was higher for those with no formal qualifications (18%) than those with degree-level qualifications (10%). Similarly, there were some differences in the onset rates across different socio-economic classification. The overall onset rate was higher for those in lower supervisory and technical (18%) and semi-routine and routine occupations (16%), than those in higher managerial, administrative and professional occupations (12%).

Table 4.2, Onset rates by tenure, highest qualification [1] and NS-SEC at Wave One [2], and by age

Onset Rate
Per cent
   Working Age (16-64) 65 and over Total
Tenure
   Own it outright 12 22 16
   Buying it with the help of a mortgage or loan 11 21 11
   Pay part rent and part mortgage (shared ownership) [29] * [31]
   Rent it 13 28 14
   Live here rent-free 14 [34] 18
Highest Qualification
   Degree level qualification (or equivalent) 10 11 10
   Higher educational qualification below degree 14 15 14
   A-Levels or Highers 10 20 11
   ONC National Level BTEC 9 36 10
   O Level or GCSE equivalent (Grade A-C) 12 14 12
   GCSE grade D-G or CSE grade 2-5 or Standard Grade level 4-6 12 8 12
   Other qualifications (including foreign qualifications) 11 18 12
   No formal qualifications 17 22 18
Socio-economic classification (based on occupation)
   Higher managerial, administrative and professional 11 18 12
   Intermediate occupations 13 22 14
   Small employers and own account workers 10 24 12
   Lower supervisory and technical occupations 15 31 18
   Semi-routine and routine occupations 13 25 16

Table source: Office for National Statistics

Table notes:

  1. Qualifications were asked of those aged 16 to 69.
  2. Socio-economic classification is based on current occupation. Occupation was also asked of those who are not currently employed but had last worked within the past eight years.
  3. See appendix 8 for sample size.
  4. * Cells have been suppressed due to small cell counts.
  5. [ ] Figures should be used with extra caution because they are based on fewer than 30 reporting individuals.
  6. All percentages have been rounded to the nearest 1.
  7. This data was revised on April 10th 2014.

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Notes for 4.2 Onset of impairment by demographic characteristics

  1. Wave One characteristics are used here due to the complex sampling on LOS. Adults who did not have an impairment at Wave One and who were not selected in Impairment or Control Households, only received a face-to-face interview at Wave Two if they reported an onset of impairment during the keeping in touch exercise prior to Wave Two. It is therefore not possible to report on Wave Two characteristics for these people.

  2. https://www.gov.uk/government/collections/english-housing-survey

4.3 Impairments reported by adults experiencing onset of impairment at Wave Two

Figure 4.1 shows the number of impairments experienced by onset-acquired adults at Wave Two. Adults who were onset-acquired at Wave Two were most likely to report only one impairment (69%), 18% had two impairments and a further 12% had three or more impairments. Adults of working age were more likely to report just one impairment (73%), than those aged 65 and over (60%). Those aged 65 and over were much more likely to experience onset of three or more impairments (19%) than those of working age (10%).

Figure 4.2 shows long-term pain, chronic health condition1, mobility and dexterity2 (55%, 33%, 12% and 8% respectively) were the four most commonly-reported impairments by adults who were onset-acquired at Wave Two. The least commonly reported impairments by adults who had experienced impairment onset were speaking, behavioural or intellectual impairment (all 1%). The distribution of impairment types among onset-acquired adults at Wave Two was very similar to the distribution of impairment types reported by adults with impairment at both waves (see Figure 2.2) and offset adults (see Figure 3.2).

 

Figure 4.3 shows the impairments experienced by onset-acquired adults split by age. It is interesting to note that while the proportion of adults experiencing onset of the two most common types of impairments (long-term pain and chronic health condition) are similar for adults of working age and those aged 65 and over, a larger proportion of those aged 65 and over than working age adults reported an onset of mobility (26% compared with 7%), dexterity (14% compared with 5%), and hearing impairments (11% compared with 5%). On the other hand, a higher percentage of working age adults reported the onset of a mental health condition (9% compared with 2%) and learning (6% compared with 1%) impairments than those aged 65 and over.

Figure 4.1 Onset-acquired: Number of impairments reported at Wave Two, by age

Most onset-acquired adults had only 1 impairment at Wave Two.
Source: Life Opportunities Survey - Office for National Statistics

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Figure 4.2 Onset-acquired: Impairment types reported at Wave Two

The most common impairment types were long-term pain and chronic health condition.
Source: Life Opportunities Survey - Office for National Statistics

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Figure 4.3 Onset-acquired: Impairment types reported at Wave Two, by age

Adults aged 65 and over were more likely to have mobility and dexterity impairments, while working age adults were more likely to have mental health condition and learning impairments.
Source: Life Opportunities Survey - Office for National Statistics

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Notes for 4.3 Impairments reported by adults experiencing onset of impairment at Wave Two

  1. Chronic Conditions are defined as long-term conditions that have lasted or are expected to last 12 months or more and that have been diagnosed by a health professional. These include but are not limited to: Asthma or severe allergies; Heart condition or disease; Kidney condition or disease; Cancer; Diabetes; Epilepsy; Cerebral Palsy; Spina Bifida; Cystic Fibrosis; Muscular Dystrophy; Migraines; Arthritis or rheumatism; Multiple Sclerosis (MS) ; Paralysis of any kind; and Depression;

  2. Respondents were able to report more than one impairment, therefore the percentages may sum to more than 100.

4.4 Severity of impairment reported by onset-acquired adults

The severity of an impairment can be reflected by both the level of difficulty and frequency of the limitation associated with the impairment. According to the LOS definition, only those respondents who rated their level of pain to be moderate or higher and the frequency of the limitation to be greater than “never” were identified as having that impairment.

In general, adults who were onset-acquired at Wave Two were most likely to rate the severity of their impairments as low in terms of both the level (“moderate”) and the frequency (“rarely” or “sometimes”) of the limitation they experienced.

Tables 4.3 to 4.6 show the severity in terms of limitation and frequency scales for the four most commonly reported impairments by adults who were onset-acquired at Wave Two: long-term pain, chronic health condition, mobility, and dexterity1

For each impairment, the majority of adults (80% or greater for all four impairment types) experienced moderate difficulty, rather than higher levels of difficulty (severe or cannot do) at Wave Two. For each of these four impairments, a large proportion (40% to 54%) of adults also rated the frequency of limitation to be “sometimes”. However, reasonably high percentages of all onset-acquired adults also reported frequency of limitation as “often” or “always” (for example 15% of all adults reported frequency of limitation for long-term pain as “often” and 10% as “always”), so onset was not limited to only those in the “rarely” and “sometimes” frequency groups.

The proportions of onset-acquired adults reporting moderate or severe difficulty do not appear to be associated with age: the proportions reporting moderate limitation among working age adults was very similar to the proportion of those aged 65 and over reporting the same level of pain, across all four impairment types.

The proportion of adults with onset of a mobility impairment at Wave Two were nearly three times as likely to ‘always’ experience difficulty, compared with onset-acquired adults who had long-term pain (27% compared with 10%).

Adults aged 65 and over who experienced onset of a chronic health condition or a dexterity impairment were more likely to “always” experience difficulty and less likely to “sometimes” experience difficulty than their working age equivalents. For example, among adults who experienced an onset of a chronic health condition, 26% of those aged 65 and over “always” experienced difficulty compared with 13% of working age adults, and 43% of adults aged 65 and over “sometimes” experienced difficulty compared with 51% of adults of working age.

Table 4.3, Onset-acquired: impairment types reported at Wave Two, by age

  Frequency of limitation    
    Rarely Sometimes Often Always Total Sample Size (100%)
Level of pain1            
   Working Age (16-64)
          Moderate difficulty 21 46 10 5 82  
          Severe difficulty 2 9 4 3 18  
          Total 24 55 14 7   580
   65 and Over            
          Moderate difficulty 13 38 14 13 78  
          Severe difficulty 2 11 4 5 22  
          Total 15 49 19 17   330
   All Onset-acquired            
          Moderate difficulty 19 44 11 7 81  
          Severe difficulty 2 9 4 3 19  
          Total 22 54 15 10   910

Table source: Office for National Statistics

Table notes:

  1. * - Values suppressed due to small cell counts.
  2. All percentages have been rounded to the nearest 1
  3. This data was revised on April 10th 2014.

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Table 4.4, Onset-acquired: severity of chronic health condition at Wave Two, by age

 
Per cent
   Frequency of Limitation   
  Rarely Sometimes Often Always Total Sample Size (100%)
Level of difficulty1            
   Working Age (16-64)
          Moderate difficulty 9 47 18 6 80
          Severe difficulty 3 4 6 7 20
          Total 13 51 24 13 310
   65 and over
          Moderate difficulty 8 34 20 19 81
          Severe difficulty * 8 3 7 19
          Total 9 43 23 26 210
   All Onset-acquired
          Moderate difficulty 9 43 18 10 80
          Severe difficulty 3 5 5 7 20
          Total 12 48 24 16 530

Table source: Office for National Statistics

Table notes:

  1. Response categories for level of difficulty: 1. “No Difficulty”; 2. “Mild Difficulty”; 3. “Moderate Difficulty”; 4. “Severe Difficulty”; and 5. “Cannot do”; For some impairment types (chronic condition, breathing, learning, intellectual, behavioural, memory and mental impairments), the levels range from 1 to 4. For pain, the level of pain is measured by the intensity of the pain experienced: 1”Mild”; 2.”Moderate”; 3. “Severe”.
  2. * Cells have been suppressed due to small cell counts.
  3. Sample sizes have been rounded independently to the nearest 10.
  4. All percentages have been rounded to the nearest 1.
  5. This data was revised on April 10th 2014.

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Table 4.5, Onset-acquired: severity of mobility impairment at Wave Two, by age

Per Cent
    Frequency of Limitation        
  Rarely Sometimes Often Always Total Sample Size (100%)
Level of difficulty1            
   Working Age (16-64)
          Moderate difficulty 2 54 19 12 88
          Severe difficulty 0 * 3 7 12
          Cannot do1 0 0 0 0 0
          Total 2 56 22 19 80
   65 and over
          Moderate difficulty 4 36 25 21 86
          Severe difficulty 0 * 1 12 14
          Cannot do 0 0 0 * *
          Total 4 37 26 33 160
   All Onset-acquired
          Moderate difficulty 3 44 22 17 87
          Severe difficulty 0 1 2 10 13
          Cannot do 0 0 0 * *
          Total 3 46 24 27   230
 

Table source: Office for National Statistics

Table notes:

  1. Response categories for level of difficulty: 1. “No Difficulty”; 2. “Mild Difficulty”; 3. “Moderate Difficulty”; 4. “Severe Difficulty”; and 5. “Cannot do”; For some impairment types (chronic condition, breathing, learning, intellectual, behavioural, memory and mental impairments), the levels range from 1 to 4. For pain, the level of pain is measured by the intensity of the pain experienced: 1”Mild”; 2.”Moderate”; 3. “Severe”.
  2. * Cells have been suppressed due to small cell counts
  3. 0 - Less than 0.5 per cent, including none.
  4. Sample sizes have been rounded independently to the nearest 10
  5. All percentages have been rounded to the nearest 1
  6. This data was revised on April 10th 2014

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Table 4.6, Onset-acquired: severity of dexterity impairment at Wave Two, by age

 
Per Cent
      Frequency of limitation      
   Rarely Sometimes Often Always Total Sample Size (100%)
Level of difficulty1
   Working Age (16-64)
          Moderate difficulty 7 40 25 10 81
          Severe difficulty * * * 8 18
          Cannot do1 0 0 * 0 *
          Total 8 43 31 18 60
   65 and over
          Moderate difficulty 11 37 17 19 84
          Severe difficulty * * 4 10 15
          Cannot do 0 0 * 0 *
          Total 11 38 22 29 100
   All Onset- acquired
          Moderate difficulty 9 38 21 15 83
          Severe difficulty * 2 4 9 16
          Cannot do 0 0 * 0 *
          Total 10 40 26 23   160

Table source: Office for National Statistics

Table notes:

  1. Response categories for level of difficulty: 1. “No Difficulty”; 2. “Mild Difficulty”; 3. “Moderate Difficulty”; 4. “Severe Difficulty”; and 5. “Cannot do”; For some impairment types (chronic condition, breathing, learning, intellectual, behavioural, memory and mental impairments), the levels range from 1 to 4. For pain, the level of pain is measured by the intensity of the pain experienced: 1”Mild”; 2.”Moderate”; 3. “Severe”.
  2. * Cells have been suppressed due to small cell counts.
  3. 0 - Less than 0.5 per cent, including none.
  4. Sample sizes have been rounded independently to the nearest 10.
  5. All percentages have been rounded to the nearest 1.
  6. This data was revised on April 10th 2014.

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Notes for 4.4 Severity of impairment reported by onset-acquired adults

  1. Corresponding figures for other impairments or health conditions can be found in Annex 5.

4.5 Onset rates of impairment types

Longitudinal data allow onset rates to be calculated for each impairment type. The onset rates used in this report have been calculated as the percentage of all people without any impairment at Wave One, who subsequently reported a specific impairment at Wave Two. Analysis in this section has been restricted to looking at the onset rates for onset-acquired adults. Adults with impairment at both waves can also experience an onset of impairment; these adults are not included in this analysis. The onset rates by impairment types for adults with impairment at both waves can be found in Section 2.3.

Table 4.7 shows that the rate is higher for those aged 65 and over than for working age adults, this is most notable in long-term pain (11.5% compared with 6.6%), chronic health condition (7.9% compared with 3.8%), mobility (5.9% compared with 0.9%) and dexterity (3.3% compared with 0.6%) impairments. This is consistent with the pattern seen in Table 4.1.

Table 4.7, Onset-acquired: onset rates of impairment types, by age

Onset Rate in per cent
   Working age (16-64) 65 and over Total
Intellectual 0.1 * 0.1
Speaking 0.1 0.4 0.1
Behavioural 0.2 * 0.2
Other impairment 0.4 0.4 0.4
Learning 0.7 0.2 0.6
Memory 0.4 1.8 0.7
Breathing 0.4 2.3 0.7
Hearing 0.6 2.5 0.9
Mental health condition 1.1 0.5 1.0
Sight 0.8 2.1 1.0
Dexterity 0.6 3.3 1.0
Mobility 0.9 5.9 1.6
Chronic health condition 3.8 7.9 4.4
Long-term pain 6.6 11.5 7.3
Sample size (100%)1 13,860 3,380 17,240

Table source: Office for National Statistics

Table notes:

  1. See Appendix 8 for sample sizes.
  2. * Cells have been suppressed due to small cell counts.
  3. Sample sizes have been rounded independently to the nearest 10.
  4. All percentages have been rounded to the nearest 0.1.
  5. This data was revised on April 10th 2014.

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4.6 Onset of impairment due to an increase in severity

In order for an adult to be classified as having an impairment, according to the LOS definition, he/she has to report the impairment and experience more than ‘mild’ difficulty and a degree of limitation as a consequence of the impairment. It is therefore possible that some impairment onsets identified at Wave Two may actually be a result of a change in the level of difficulty reported for the impairment from ‘mild’ to more severe levels, rather than the onset of a new previously unreported1 impairment between Wave One and Two.

For example, an adult may report a dexterity impairment at Wave One, but because the level of difficulty experienced was ‘mild’ he/she was not classified by LOS as an adult with a dexterity impairment. At Wave Two the same adult may again report a dexterity impairment but if by this time the level of difficulty experienced has increased to ‘moderate’ (or above), he/she will be classified by LOS as having a dexterity impairment at Wave Two.

Table 4.8 shows the onset rate for the four most commonly-reported impairment types overall, split by adults who experienced an onset of impairment at Wave Two because the difficulty level experienced increased from ‘mild’ (onset from mild), and by adults who experienced an onset of impairment at Wave Two because they reported that impairment for the first time (complete onset). These figures are presented alongside the overall onset rates from Table 4.7. Corresponding figures for the other impairment or health condition types can be found in Appendix 8.

More than half of adults who experienced onset of a chronic health condition had previously reported mild difficulty associated with this impairment. This indicates that the course of onset for chronic health condition might occur over a long period. In contrast, a lower proportion of dexterity impairment and long term pain onset can be explained by an increase in the level of difficulty experienced; this could indicate that dexterity impairment develops more quickly than chronic health condition, or that a dexterity impairment is unlikely to cause mild difficulty.

Table 4.8, Onset-Acquired: onset due to an increase from mild difficulty at Wave One, by age

  Overall onset rate Onset from mild  ('mild difficulty' reported at Wave One) Complete onset (impairment not reported at Wave One)
Long-Term Pain    
   Working Age (16-64) 6.6 1 5.6
   65 and Over 11.5 2.1 9.4
   Total 7.3 1.1 6.2
Chronic Condition    
   Working Age (16-64) 3.8 1.8 2
   65 and Over 7.9 5.9 1.9
   Total 4.4 2.5 2
Mobility    
   Working Age (16-64) 0.9 0.1 0.7
   65 and Over 5.9 2.6 3.3
   Total 1.6 0.5 1.1
Dexterity    
   Working Age (16-64) 0.6 0.1 0.5
   65 and Over 3.3 0.8 2.5
   Total 1 0.2 0.8
 

Table source: Office for National Statistics

Table notes:

  1. See Appendix 8 for sample size
  2. All percentages have been rounded to the nearest 0.1
  3. This data was revised on April 10th 2014

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Notes for 4.6 Onset of impairment due to an increase in severity

  1. LOS collects information about impairments experienced by the respondent at the time of the interview. Respondents may have experienced periods of impairment prior to their participation in LOS that were not recorded at Wave One because the respondent was not experiencing that impairment at that time.

Background notes

  1. Details of the policy governing the release of new data are available by visiting www.statisticsauthority.gov.uk/assessment/code-of-practice/index.html or from the Media Relations Office email: media.relations@ons.gsi.gov.uk

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