Physical and mental strain at work: Relationships with onset and persistent of multi-site pain in a four-year follow up

1 Physical and men al s ain a wo k: Rela ionships wi h onse and pe sis ence o mul i-si e pain in a ou -yea ollow up Subas Neupane1, 2 *, Clas-Håkan Nygå d1, 2 1School o Heal h Sciences FI – 33014, Uni e si y o Tampe e, Tampe e Finland 2Ge on ology Resea ch Cen e , FI – 33014, Uni e si y o Tampe e *Co esponding au ho : D . Subas Neupane School o Heal h Science FI – 33014 Uni e si y o Tampe e, Finland Email subas.neupane@u a. i Phone +358 40 1909709 Fax +358 3 35516057 Running i le: Men al and physical s ain and mul i-si e pain 2 Abs ac This s udy e alua es whe he physical and men al s ain a e associa ed wi h an onse and pe sis ence o mul i-si e pain among younge and olde employees in a ou yea o ollow- up. A ques ionnai e su ey was conduc ed in a ood p ocessing company wice, in 2005 and 2009 wi h he esponse om 734 employees in he age be ween 20 and 66 yea s (445 younge and 289 olde ; 65% emale). In o ma ion on musculoskele al pain du ing he p eceding week and pe cei ed men al and physical s ain was ob ained h ough a s uc u ed ques ionnai e. The associa ion o onse and pe sis ence o mul i-si e pain wi h men al and physical s ain was es ima ed wi h log binomial eg ession analysis and s a i ied by age- g oup. Risk a io (RR) wi h hei 95% con idence in e als (CIs) a e epo ed o he es ima es. Mo e han 56% o he employees epo ed mul i-si e pain a baseline. Among hose who epo ed mul i-si e pain a baseline 70% epo ed pe sis ence o mul i-si e pain and one hi d had new onse o mul i-si e pain a he ollow-up. Men al s ain a baseline s ongly p edic ed pe sis ence o mul i-si e pain among bo h younge and olde employees (RR om o younge employees = 1.68, 95% CI = 1.01-2.83 and RR o olde employees = 2.25, 95% CI 0 1.27-3.98). The high men al s ain p edic ed he isk o pe sis ence mul i- si e pain among bo h younge and olde employees in a ou yea ollow-up bu no onse o mul i-si e pain. Key wo ds: musculoskele al pain; mul i-si e pain; men al s ain; physical s ain 3 Highligh s •The e is an inc eased a en ion o he ela ionship be ween wo k exposu es and musculoskele al diso de s in ecen esea ch. •Men al s ain a baseline was s ong p edic o o pe sis ence o mul i-si e pain musculoskele al pain bo h among younge and olde employees. •In e en ions in he wo kplaces ocusing on he indi idual le el would educe physical and men al s ain as a esul lowe he incidence o mul i-si e pain o bo h younge and olde employees. 4 INTRODUCTION Musculoskele al pain in mul iple body si es is equen in he wo king popula ion (Neupane e al, 2013a; Haukka e al, 2013; He in e al, 2014). A la ge body o esea ch howe e ocused on a single body si e. Associa ion be ween ce ain physical (physical wo k load, epe i i e ask, awkwa d pos u e) and psychosocial exposu es (high job demands, low job con ol, co-wo ke s and supe iso s suppo ) a wo k and pain ul condi ions a pa icula ana omical si es has been s udied ex ensi ely. E idence shows ha pain in mul iple body si e is associa ed wi h dec eased unc ioning and wo se p ognosis when compa ed o ha ing pain in only one body si e (Neupane e al, 2014; Haukka e al, 2013; Kamale i e al, 2008; Mi anda e al, 2010). Howe e less is known abou he ela ionship o mul i-si e musculoskele al pain wi h men al and physical s ain ela ed wo k exposu es. The concep o s ain in his s udy is based on he s ess-s ain model whe e he s ess on a wo ke depends on en i onmen al ac o s (bo h physical and psychosocial) ac ing upon he pe son, whe eas s ain deno es he e ec s o s ess which di e by indi idual o a ce ain s ess ac o (Ru en an z, 1981; Cox e al, 2000). The s ess and s ain concep has been widely used in s udies on he e ec s o physical wo k load on bo h he ca dio ascula as well as he musculoskele al sys em (Ru en anz, 1981, Nygå d e al, 1988). The model emphasizes he ole o indi idual cha ac e is ics such as age, gende , heal h s a us and wo k abili y as modi ie s o he ela ionship be ween s ain and musculoskele al symp oms o pain. 5 Indus ial wo ke s a e mos ly exposed o physical s ain (Nico , 2007). The high s ain is mos ly due o he physical wo k en i onmen in he indus y. In a c oss-sec ional s udy among men and women employed in di e en occupa ions, physical s ain was associa ed wi h musculoskele al symp oms (Johansson, 1995). One ea lie s udy among heal h ca e employees, men al s ain was ound o be a isk ac o o musculoskele al symp oms in a h ee yea ollow-up (Josephson e al, 1997). I also ound ha he isk was highe when i was combined wi h pe cei ed high physical exe ion. Psychological o men al s ain has also been ound o be linked o poo ou comes such as ea ly e i emen (Laine e al, 2008) and mo ali y (Ki imäki e al, 2002). In a 28 yea s o ollow-up s udy, wo k s ain (bo h men al and physical) du ing midli e among municipal employees was ound o be s ongly ela ed o declined wo k abili y in old age ( on Bonsdo e al, 2012) and s ess symp oms in midli e p edic ed disabili y a e 28 yea s (Kulmala e al, 2013). Ea lie s udies ha e epo ed he ela ionship o s ain and age wi h inconclusi e indings. One s udy has shown ha olde employees expe ience highe s ain han younge employees (Nygå d e al., 1997). Howe e , Pailhe (2005) epo ed ha younge coho s a e exposed o physical s ain mo e equen ly han olde coho s. In his s udy o 4 yea s o p ospec i e ollow-up o indus ial employees we e alua ed whe he physical and men al s ain we e associa ed wi h an onse and pe sis ence o mul i-si e pain. We we e also in e es ed whe he he associa ion we e di e en o younge and olde employees. METHODS 6 This s udy is based on ques ionnai e su eys conduc ed among all employees o one o he leading ood indus ies in Finland (1985 employees) in sp ing 2005 and sp ing 2009. The ques ionnai es we e dis ibu ed a he wo kplaces o e e y employee ( esponse a e 60%). I was possible o eply anonymously o o sign he consen o indi idual ollow-up o he su eys and o linking o he pe sonnel egis e s o he company including in o ma ion on age, gende occupa ional s a us, wo kplace and du a ion and in e up ions o he job con ac . The eplies we e placed in sealed en elopes which we e collec ed and o wa ded o he esea che s. As he ques ion o ms we e no add essed o indi idual employees, no eminde s could be sen . The s udy was app o ed by he e hical commi ee o Pi kanmaa Hospi al Dis ic . Measu emen o a iables A modi ica ion o he alida ed No dic Musculoskele al ques ionnai e (Kuo inka e al. 1987) was used o assess musculoskele al pain. I included a ques ion ega ding whe he he employee had el pain, aching o numbness in ou ana omical a eas (hands o uppe ex emi ies; neck o shoulde s; lowe back; and ee o lowe ex emi ies) du ing he p eceding week, wi h he eply scale being om 0 (no a all) o 10 ( e y much). The a iables we e dicho omised a he median (less han median: 0= mild; mo e han median: 1= se e e). The cu -o alues o uppe ex emi ies, neck and shoulde , lowe back and lowe ex emi ies we e 4, 5, 2 and 2, espec i ely. The dicho omised a iables we e summed up in o a a iable exp essing he numbe o a eas wi h se e e pain ( om ze o o ou ) (Neupane e al. 2013a; Neupane e al. 2013b). The summed a iable was u he 7 ca ego ized in o wo, lea ing ze o and one as ‘no mul i-si e pain’ and ‘mul i-si e pain’ by combining wo, h ee and ou si es pain. Men al s ain Pe cei ed men al s ain was assessed by a modi ied e sion o he occupa ional s ess ques ionnai e (Elo e al., 1992), using a single ques ion (“S ess means a si ua ion in which a pe son eels exci ed, app ehensi e/conce ned, ne ous o dis essed o she/he canno sleep because o he hings on he /his mind. Do you eel his kind o s ess nowadays?”) (Elo e al., 1992), wi h he eply scale om 0 (no a all) o10 ( e y much). Fo his analysis, men al s ain was ca ego ized in o low (0-2), medium (3-6) and high (7-10) by hei e ile alues. Physical s ain Pe cei ed physical s ain was elici ed wi h he a ing o pe cei ed exe ion (RPE) wi h he ques ion “How physically ha d/ exhaus ing do you eel you job is in a no mal wo k day?” on a scale om 6 (no a all) o 20 ( e y much) (Bo g, 1970). Physical s ain in his s udy was ca ego ized in o h ee low (6-11), medium (12-15) and high (16-20) based on he e ile alues. Co a ia es: Wo k abili y was assessed wi h one ques ion om he wo k abili y index as a subjec i e assessmen o cu en wo k abili y compa ed wi h a pe son’s sel -iden i ied li e ime bes (i.e. wi h he ques ion “Assume ha you wo k abili y a i s bes has a alue o 10 poin s. 8 Wha sco e would you gi e you cu en wo k abili y?”). Wo k abili y was ca ego ized in o excellen (sco e 10), good (sco e 9), mode a e (sco e 8) and poo (sco es 0-7) wo k abili y in his s udy (Gould e al, 2008). Body mass index (BMI) was calcula ed using wo ke s’ sel - epo ed weigh (kg) and heigh (m). The le el o physical exe cise du ing he las mon h was elici ed on a scale om 0 (no a all) o 7 (s enuous physical ac i i y o mo e han 3 hou s a week). S a is ical Analysis Desc ip i e s a is ics o he s udy popula ion was p esen ed i s in he o m o equencies and pe cen ages in o al s a i ied by age g oup (<45 yea s ‘younge ’ and ≥45 ‘olde ’). Log binomial eg ession analysis was pe o med o examine whe he baseline men al and physical s ain we e associa ed o mul i-si e pain a e ou yea s o ollow-up. Risk a ios (RR) wi h hei 95% con idence in e als (CI) a e p esen ed. The analyses we e conduc ed sepa a ely o hose who had mul i-si e pain a baseline ('pe sis ence o mul i-si e pain') and hose wi h no mul i-si e pain a baseline (‘onse o mul i-si e pain’). And again bo h analyses we e s a i ied by age g oup in o de o see he di e ence be ween age g oup. The models we e buil up in 3 s eps: Model I: c ude isk a ios, Model II: adjus ed o gende and occupa ional s a us and las ly Model III: includes gende , occupa ional s a us, physical exe cise, BMI and baseline wo k abili y. All he analyses we e ca ied ou wi h he s a is ical package SPSS e sion 21.0. RESULTS 9 Table 1 shows he desc ip i e cha ac e is ics o he s udy popula ion a baseline. Wi hin he o al o 734 s udy popula ion, 60% we e less han 45 yea s o old. Abou wo hi d o he s udy popula ion we e emale and mo e han 70% we e blue-colla employees. The e we e mo e male and blue-colla employees in he younge age g oup and mo e emale and whi e-colla employees in he olde age. One hi d o he s udy popula ion had high physical exe cise which no much di e ed be ween age g oups. A li le mo e han one i h o he people had BMI ≥ 29.0 Kg/m2 and almos 30% o he younge employees had low (<23.0 kg/m2) BMI and 25% o he olde employees had high (≥ 29.0 Kg/m2) BMI. Abou 15% o he s udy popula ion had poo wo k abili y a baseline and abou he same numbe (16%) had epo ed excellen wo k abili y. Wi hin he age g oup, almos one i h o younge employees had excellen wo k abili y compa ed o 11% in hei olde coun e pa s. Physical s ain was compa a i ely high (30% s. 27%) among younge employees while men al s ain was high among olde employees (30% s. 21%). Mo e han 56% o he employees epo ed mul i-si e pain a baseline. Compa a i ely younge employees epo ed mul i-si e pain mo e o en han hei olde coun e pa s. Risk a ios and hei 95% CI o mul i-si e pain a ollow-up due o physical and men al s ain among he coho wi h no mul i-si e pain a baseline a e p esen ed in Table 2. One hi d o he s udy popula ion had new onse o mul i-si e pain. High physical s ain was ound o be associa ed wi h onse o mul i-si e pain among all in he c ude model (RR = 1.48, 95% CI = 1.01-2.18) bu signi icance associa ion was los when adjus ed in model II and model III. Al hough no signi ican , he employees wi h high men al s ain had highe isk o ha ing new onse o mul i-si e pain in he ou yea ollow-up. Employees wi h high 16 Hannan, L.M., Mon eilh, C.P., Ge , F., Kleinbaum, D.G., and Ma cus, M., 2005. Job s ain and isk o musculoskele al sysmp oms among a p ospec i e coho o occupa ional compu e use s. Scand. J. Wo k En i on. Heal h 31, 375-386. 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Heal h 51, 180-192. 20 Table 1: Baseline cha ac e is ics o he s udy popula ion Cha ac e is ics All Younge (<45 yea s) Olde (≥45 yea s) N=734 % N=445 % N=289 % Gende Male 255 34.7 173 38.9 82 28.4 Female 479 65.3 272 61.1 207 71.6 Occupa ional s a us Blue-colla 518 70.6 327 73.5 191 66.1 Whi e-colla 216 29.4 118 26.5 98 33.9 Physical exe cise Less 322 44.1 193 43.6 129 44.9 Mode a e 162 22.2 94 21.2 68 23.7 High 246 33.7 156 35.2 90 31.4 BMI <23.0 180 24.5 129 29.0 51 17.6 23.0-25.9 230 31.3 136 30.6 94 32.5 26.0-28.9 153 20.8 82 18.4 71 24.6 ≥29.0 171 23.3 98 22.0 73 25.3 Wo k abili y Poo 106 14.5 63 14.3 43 14.9 Mode a e 235 32.1 130 29.4 105 36.3 Good 274 37.5 165 37.3 109 37.7 Excellen 116 15.9 84 19.0 32 11.1 Physical s ain Low 247 33.7 140 31.5 107 37.2 Medium 273 37.3 169 38.1 104 36.1 High 212 29.0 135 30.4 77 26.7 Men al S ain Low 267 36.4 166 37.4 101 34.9 Medium 288 39.3 186 41.9 102 35.3 High 178 24.3 92 20.7 86 29.8 Musculoskele al pain No mul i-si e 321 43.7 191 42.9 130 45.0 Mul i-si e pain 413 56.3 254 57.1 159 55.0 21 Table 2: Risk a ios (RR) and 95% con idence in e al (CI) o mul i-si e pain in ela ion o physical and men al s ain a wo k among he coho wi h no mul i-si e pain a baseline (N=108), younge and olde employees RR and 95% CI o mul i-si e pain Model I Model II Model III All Physical s ain Low 1.0 1.0 1.0 Medium 1.12 (0.81-1.55) 1.02 (0.70-1.48) 1.09 (0.74-1.60) High 1.48 (1.01-2.18) 1.29 (0.83-2.00) 1.38 (0.87-2.18) Men al S ain Low 1.0 1.0 1.0 Medium 1.22 (0.89-1.67) 1.27 (0.92-1.75) 1.14 (0.82-1.60) High 1.19 (0.80-1.78) 1.28 (0.85-1.94) 1.23 (0.80-1.88) Younge Physical s ain Low 1.0 1.0 1.0 Medium 1.20 (0.79-1.82) 1.16 (0.71-1.91) 1.40 (0.82-2.41) High 1.39 (0.80-2.41) 1.34 (0.72-2.47) 1.69 (0.88-3.25) Men al S ain Low 1.0 1.0 1.0 Medium 1.14 (0.76-1.71) 1.17 (0.78-1.77) 1.05 (0.68-1.62) High 0.90 (0.49-1.66) 0.99 (0.53-1.87) 1.08 (0.56-2.10) Olde Physical s ain Low 1.0 1.0 1.0 Medium 1.11 (0.65-1.87) 0.93 (0.52-1.65) 0.91 (0.50-1.66) High 1.53 (0.89-2.64) 1.18 (0.62-2.24) 1.12 (0.57-2.20) Men al S ain Low 1.0 1.0 1.0 Medium 1.31 (0.79-2.17) 1.38 (0.82-2.30) 1.28 80.74-2.21) High 1.36 (0.77-2.40) 1.46 (0.82-2.61) 1.39 (0.75-2.55) Model I: C ude isk a io Model II: Adjus ed o gende and occupa ional s a us Model III: Adjus ed o model II + physical exe cise, BMI and wo k abili y a baseline 22 Table 3: Risk a ios (RR) and 95% con idence in e al (CI) o mul i-si e pain in ela ion o physical and men al s ain a wo k among he coho wi h mul i-si e pain a baseline (N=291), younge and olde employees RR and 95% CI o mul i-si e pain Model I Model II Model III All Physical s ain Low 1.0 1.0 1.0 Medium 1.02 (0.74-1.41) 1.05 (0.73-1.50) 0.97 (0.66-1.42) High 1.46 (1.04-2.04) 1.52 (1.02-2.24) 1.28 (0.85-1.94) Men al S ain Low 1.0 1.0 1.0 Medium 1.44 (1.07-1.95) 1.45 (1.07-1.97) 1.40 (1.01-1.93) High 2.07 (1.47-2.92) 2.24 (1.57-3.20) 1.90 (1.30-2.78) Younge Physical s ain Low 1.0 1.0 1.0 Medium 1.00 (0.65-1.53) 1.03 (0.64-1.67) 0.97 (0.58-1.62) High 1.57 (1.03-2.41) 1.63 (1.00-2.73) 1.40 (0.81-2.42) Men al S ain Low 1.0 1.0 1.0 Medium 1.37 (0.93-2.01) 1.37 (0.93-2.01) 1.21 (0.80-1.84) High 1.96 (1.24-3.10) 2.15 (1.33-3.45) 1.68 (1.01-2.83) Olde Physical s ain Low 1.0 1.0 1.0 Medium 1.04 (0.64-1.71) 1.07 (0.62-1.83) 0.92 (0.51-1.65) High 1.25 (0.72-2.17) 1.30 (0.70-2.41) 1.00 (0.52-1.93) Men al S ain Low 1.0 1.0 1.0 Medium 1.54 (0.94-2.53) 1.56 (0.94-2.56) 1.63 (0.96-2.78) High 2.24 (1.33-3.77) 2.42 (1.41-4.15) 2.25 (1.27-3.98) Model I: C ude isk a io Model II: Adjus ed o gende and occupa ional s a us Model III: Adjus ed o model II + physical exe cise, BMI and wo k abili y a baseline